JPH06169476A - Method and apparatus for measurement of convergence of color picture tube - Google Patents

Abstract

PURPOSE: To precisely determine the position of an electron beam in the horizontal direction by using a square electron distribution pattern standing on one apex. CONSTITUTION: A square electron pattern of each of three colors R, G, and B standing on one apex is generated by a pattern generator 10 and is inputted to a picture tube 11, and a luminance distribution pattern on a screen 14 is converted to an electric charge pattern through a picture converter 15 and is stored in a RAM 18. The variable position value of the electric charge pattern is analyzed from this data by an analysis logic unit 19 to measure the position of the electron beam. Thus, the edge part is extended at an angle to the lengthwise direction of a mask slot, and the quick change due to slight displacement of the electron beam can be eliminated, and the position of the electron beam in the horizontal direction is precisely measured and determined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for measuring the position of an electron beam in a multi-beam color picture tube with respect to the visual field of an image converter.

[0002]

In practice, such methods and apparatus are used to determine convergence error and vertical raster offset. Convergence measurements measure the position of raster lines produced by at least two electron beams. Deviation between positions indicates convergence error. The vertical raster offset determines the extent to which the horizontal raster line deviates vertically from the horizontal centerline of the color picture tube.

A device for measuring convergence and vertical raster position has been commercially available for several years (Innovation Technique GmbH, Bremen, Germany), and will be described below with reference to the drawings in FIGS. Has been done. The processing performed by this device will be described with reference to FIGS.

The known device according to FIG. 7 comprises a pattern generator 10 'for driving an electron beam generating system 12 aligned with the neck of a color picture tube 11 and a deflecting device 13.
The image produced by the screen 14 of the tube is recorded by the image converter camera 15 and analyzed by the analyzer 16 '. Pattern generator 10 'and image converter camera 15
The sequence generated by the analyzer 16 'over time is controlled by the sequence controller 17'. Analyzer 1
6'is RAM 18, analysis logic unit 19 ', display 2
Has 0.

A CCD converter 21 is arranged in the image converter camera 15, and the structure thereof is shown in FIG. A CCD converter under the control of the sequence control device 17.
The charges accumulated in the 21 images are read and digital 8
The bit value is assigned to the charge quantity. One RAM cell corresponds to each CCD pixel. The pseudo address of RAM18 is R
The arrangement of AM cells corresponds to the arrangement of CCD pixels. From this, it is clear that the information pattern stored in the RAM directly corresponds to the charge pattern previously stored in the CCD and the brightness distribution pattern generated on the screen 14. Each RAM has a capacity of 10 ¹⁸ [sic; 2 ¹⁸ ] cells equal to 256 kilobytes.

The pattern produced by the pattern generator 10 'is a conventional grid pattern consisting of one horizontal line and one vertical line for each of the three colors of the color picture tube. FIG. 9 shows the appearance of the vertical line emission screen 14.

The light emitting screen 14 is a fluorescent stripe R,
It is composed of G and B and matrix stripes located between them, and is shown by narrow cross hatching in FIG. There is a point where the electron spot collides with the emission screen and the fluorescent stripe, and light emission occurs in the emission color of the fluorescent stripe. Domains that emit red light are identified by a dashed line in the upper right, domains that emit green light are identified by continuous line hatching, and domains that emit blue light are identified by a downward right hatching. Each emission spot has a width of 200 μm and a height of 700 μm. Light emission spots belonging to the same color in the horizontal direction are separated by an interval of 810 μm, and vertically, they are separated by an interval of 100 μm.
These values apply to the center of the emission screen. The fluorescent stripes and the matrix stripe become wider toward the outer edge. Similar size ratios apply if matrix stripes are not present. In this case the fluorescent stripes are separated from each other by uncovered stripes and the electron spots impinge within the fluorescent stripes.

The lower half of FIG. 9 shows the image produced by a vertical raster line as a function of the fluorescent spot. The beam scans the screen 14 and in each case is exactly pulsed at a specific position or, more precisely, at a specific time after the horizontal sync pulse and is blocked again. This intensity therefore increases and then decreases. The intensity profile starting at about 10% of maximum brightness is shown in the lower half of FIG. Figure 9
In each case, it is clear that two red vertical stripes, two green vertical stripes, and two blue vertical stripes are generated, which have different intensities when considered in detail. When the screen is observed from a distance of eg 1 m, each color stripe is imperceptible and instead a single white bar is produced. However, this is true if the intensity profiles of the three beams are identical to each other, as shown in FIG. On the other hand, an electron beam that excites the red fluorescent stripe (hereinafter referred to as a red electron beam)
Is offset to the left with respect to the electron beam that excites the green fluorescent stripe (hereinafter referred to as green electron beam), and the electron beam that excites the blue fluorescent stripe (hereinafter referred to as blue electron beam) is the green electron. Three color rasters spaced apart from each other when offset to the right with respect to the beam
Stripes appear, and when observed in the vicinity, each is 810 μm.
Two stripes separated from each other by a distance of. In the case of FIG. 9, the three electron beams converge horizontally, but in the above case they do not converge.

The device according to FIG. 7 determines the position of the electron beam by determining the brightness center point of the emission spot domain produced by the particular electron beam. A process having the following steps is performed.

A pre-defined electron distribution pattern is generated on the shadow mask and the relevant brightness distribution pattern on the screen is recorded using the image converter described above to obtain the image converter. Converts the intensity distribution pattern into an electrical charge pattern and analyzes the charge pattern to obtain values characterizing various positions of the charge pattern within the field of view of the image converter.

This process is illustrated by a, b and c in FIG. In FIG. 10a, the beam has a maximum strength of at least 10
%, If the raster width of the electron beam in the range with a% intensity is slightly less than twice the distance between two adjacent fluorescent stripes of the same color. The vertical raster stripe shown in this context is positioned such that the green fluorescent stripe is located approximately in the center of its width, while the second stripe is located just at the edge. These stripes are labeled G4, G5. The relevant emission spots are shown as thick vertical bars. Potential emission spots that are not excited to emit at that time are indicated by thin vertical bars.

FIG. 10b shows the luminance distribution as measured by the CCD image converter 21 along the horizontal line and summing all signals over a pre-defined number of pixels in the vertical direction. A relatively high brightness occurs in the area of the fluorescent stripe G5, and the brightness of the area of the fluorescent stripe G4 is low.
The center point of the luminance distribution is indicated by reference sign S1V.

FIG. 10d is very similar to FIG. 10a, but slightly so that the electron beam described above occupies position MV2, especially the vertical centerline, rather than position MV1 of FIG. 10a. The difference is that it is displaced to the right. Therefore, the fluorescent stripe G4 is not located in the intensity region and instead the fluorescent stripe G6 is excited to produce a perceptible emission.
The associated intensity distribution measured by the CCD image converter 21 is shown by c in FIG. The resulting center point of the brightness profile is position SV2.

The displacement between the center points SV1 and SV2 is considerably larger than the actual displacement of the center of the electron beam from the center line MV1 to the center line MV2. Despite the small displacement, the measured position suddenly changes relatively strongly. The reason is that most of the raster lines written by the electron beam are not detected at all, and instead the small, actually colliding areas of the fluorescent stripe produce visible emission. In the case of FIG. 10a, the central fluorescent stripe also collides with the fluorescent stripe to the left, but if there is a slight displacement to the right, it does not collide with the left stripe, while the right stripe of the central fluorescent stripe suddenly changes. When bombarded, this means that 1.6 of those emitting areas present in addition to those of the central stripe are present.
mm displacement.

[0015]

The apparent jump of the vertical raster-stripe resulting from a slight displacement is shown in FIG.
The same raster stripes, as shown with reference to d, are very apparent when viewed with the naked eye without being recorded by the CCD converter 21. It is especially noticeable when the raster stripe is narrow. However, regarding the distribution of the brightness center points as well, when the raster stripe is wide, the disappearance of one light emitting stripe and the occurrence of a new light emitting stripe on the other side have almost no effect when averaging the light intensities from many light emitting stripes. Not noticeable. However, in this case the displacement can only be detected with low sensitivity. As a result, a CC having a few millimeters wide raster stripe with alignment with the naked eye and the device according to FIG.
Both with the adjustment using the D image converter.
These stripes represent a good compromise between sensitivity and interference due to the "jump" effect mentioned above.

In the vertical direction, the light emission spot is 70 in the vertical direction.
Although as high as 0 μm, they are separated from each other by only 100 μm, so the error that occurs in an improper case when the electron beam is displaced is not critical. The ratio between the emissive and non-emissive domains is therefore 7: 1, whereas in the horizontal direction it is 2: 8, a factor of 28 for the drawback of horizontal measurement.
(Regarding the correlation between measured and actual beam displacement)
Means the difference between. Due to these unfavorable situations in the horizontal direction, the known device cannot measure the horizontal convergence with sufficient accuracy.

Therefore, an existing problem is a device for measuring the position of an electron beam in a multi-beam color picture tube, which can additionally determine the position of the horizontal electron beam with high accuracy. And to provide a method.

[0018]

The method according to the invention comprises the above-mentioned steps of a known method, in which the electron distribution pattern produced has dimensions of the order of a few millimeters,
At least one edge extends obliquely with respect to the longitudinal direction of the mask slot and the associated intensity distribution pattern is imaged onto the image converter so as to perfectly match the field of view. And

The device according to the invention comprises the functional groups of the device described with reference to FIG. 7 and is patterned to produce an electron distribution pattern having dimensions on the order of a few millimeters. Is designed so that at least one edge extends obliquely to the longitudinal direction of the mask slot and the brightness distribution pattern of the image converter is matched in a manner that perfectly fits the field of view.
The image converter camera is designed to image the image.

The method according to the present invention uses the center of the luminance distribution detected by the CCD image converter when the influence of the luminescence effect in the measurement decreases from the center to the edge of the luminance pattern due to the pattern morphology. Based on the elimination of sudden changes in points. This is ensured by a pattern in which at least one edge extends obliquely to the longitudinal direction of the mask slot. The pattern is a rectangular pattern that stands at the top.
Preferably, the edges or all edges are other patterns extending obliquely to the mask slot. When such a pattern is moved horizontally across the screen,
And as new fluorescent stripes enter the pattern, or as previously existing ones move out of the pattern, the height of the pattern in these outer regions is so small that there is no effect. In addition, due to the diagonal orientation of the pattern edges, the effect of the edge stripes weakens with increasing pattern displacement until it finally exits the pattern. However, normal patterns
In stripes, the stripes either exist within the pattern along their entire length or are not contained in the pattern at all.

One very special advantage of the method and the device according to the invention is that they ensure that the convergence relation of all electron beams in the color picture tube is detected both horizontally and vertically in a single measurement. Can be designed.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The device according to the invention according to FIG. 1 is basically constructed as in FIG. 7, but the pattern generator, the sequence control device, the analysis logic unit and thus the analysis device have different functions. For this reason, these functional groups have the reference numbers 10, 17, 19, 16 instead of 10 ', 17', 19 ', 16', respectively.

As is apparent from FIG. 2a, the color picture tube 11
Is driven by a pattern generator 10 to produce a rectangular pattern that stands on top. This pattern is a few millimeters
It has an edge length of, for example, 4 millimeters, which is the reason for corresponding to the choice of stripe width of several millimeters of commonly used raster stripes. In this size, the pattern is CC according to FIG.
It fits well in the field of view A of the D image converter. The associated luminance distribution in the horizontal direction is shown in FIG. 2b. When a slight displacement to the right occurs, the light emission spot generated in the light emission stripe G6 becomes slightly longer, while the spot generated in the stripe G4 becomes slightly shorter. As shown in FIG. 2d, when the displacement to the right continues, the emission spot of the stripe G4 is shortened until it finally disappears. This therefore represents a gradual disappearance but not abrupt disappearance when the known pattern is used as explained with reference to FIG. When the new emission spots on the right do not suddenly appear for a sufficient length and instead reach the new fluorescent stripes, first short emission spots occur, which are longer for successive displacements to the right. Therefore, the emission spot cannot suddenly appear over the entire length of the field of view of the CCD image converter. These gradual changes in brightness are also evident from the brightness profiles of FIGS. 2b and 2c, which correspond to the pattern positions according to FIGS.

3a-d likewise show the situation when the rectangular pattern standing at the apex is displaced downwards. As described above, the emission spots become smaller and smaller until they finally reach the cutoff. Therefore, also in the y-direction displacement, the change in the luminance distribution also occurs without a major jump.

FIG. 4 shows that the center point of the intensity distribution need not be used to measure the displacement of the pattern. According to FIG. 4, two measuring lines ML1 and ML2 which are perpendicular to each other and extend parallel to the edges of the rectangular pattern are instead C
It is superposed on the image detected by the CD image converter 21. When the luminance analysis is moved along the measuring line ML1 from the bottom to the sum of all the luminance values occurring in the line extending perpendicularly to the measuring line ML1, the lower end of the emission spot of the fluorescent stripe G4 is the point UL1. Observed in. Prior to the signal acquisition process, the brightness values continue to be detected until the point OR1 is finally reached, and when viewed perpendicular to the line ML1, the pixels belonging to the emission spot are finally perceived. Point UL1
And OR1 characterize the lower left and upper right edges of the pattern, respectively. Correspondingly, when processed along the measurement line ML2, two points UR1 and OL1 are detected, identifying the lower right and upper left ends of the pattern, respectively. The pattern is shown in Figure 4.
Measurement point UL2 when displaced as indicated by b in FIG.
OR2 is detected similarly to UR2 and OL2. Therefore, the displacement along the measurement line is limited and 45 ° to the x direction.
Since these displacements are simply converted to x and y displacements. The analysis, which involves processing the direction of the measurement line and summing all pixel values of each line perpendicular to the measurement line, calculates the pseudo address of the direction and RAM under each pseudo address.
It can be easily done using RAM 18 by reading the cells.

With respect to the analytical variation shown in FIG. 4, the emission spots gradually enter and exit the pattern, so that the measuring points UL, UR, O when the pattern is displaced.
It is also noteworthy that there are no rapid and sudden changes in R and OL.

2-4 were used to show that the particular position measured when the pattern is continuously displaced also varies continuously rather than suddenly at some times. This is also the case when other patterns are used that have edges that extend obliquely to the mask slot rather than a square that stands at the apex, and the mask slot gradually changes the emission spot pattern. Guaranteed to leave as soon as you enter. What is essential in practical applications is that this continuous relationship between actual and observed displacement guarantees a very accurate position measurement.

In practical applications, it is not the location of each electron beam that is of interest in the x direction, but the location of multiple electron beams with respect to each other. This is shown in FIG. Each of the three electron beams of the color picture tube produces a rectangular pattern that stands at the apex. The pattern depicted by the green beam is surrounded by the solid line, the associated emission spot is characterized by the solid line bar, and the pattern produced by the red beam is surrounded by the dashed line.
The relevant emission spots are indicated by dashed lines, the pattern produced by the blue beam is surrounded by dotted lines, and the relevant emission spots are indicated by dotted stripes. If the three electron beams are convergence, the three patterns basically correspond. But this is not the case. Furthermore, it is also important to measure the offset of the red and blue beams with respect to the green-green beam in each case. For this purpose, the three positions of the three patterns should each be analyzed independently. The pattern according to FIG.
This is done even by the use of a CCD sensor by decision before storing the image, and the CCD pixel belongs to that color. For this purpose, three electron beams are operated in succession in the preparatory stage so that the color corresponding to each pixel is stored, or all the electron beams are operated simultaneously and the fluorescent triplet according to FIG. As a result of the H-shaped pattern, the structure of FIG. 9 makes it possible to assign pixels to different colors. Both methods are known from the commercially available unit according to FIG.

In measuring the vertical raster deviation, the deviation of the field of view of the image converter from the horizontal center line HA in the y direction must be detected in at least one beam, for example a green beam. The vertical displacement of the other beams is based on the green beam or the horizontal line HA. This analysis in the vertical direction is performed, for example, in the manner shown in FIG.

The device according to the invention thus provides a single storage image for all convergences and rasters in the x and y directions.
It is possible to accurately determine the position data and all electron beams. In addition to the above selection of patterns, it is necessary in advance that all patterns are maximal in the case where the fields of view A of the CCD image converters are offset with respect to each other as shown in FIG. It must be set to be within the field of view with manufacturing tolerances. This is possible with a 1: 1 image if the CCD image converter 21 according to FIG. 8 is used and a rectangular pattern with sides of about 4 mm is used. The image of the pattern stored by the camera is the CCD image when a small size CCD image converter is used, or exceptionally when tubes with large convergence and raster offset need to be tested. It has to be reduced a little by the converter.

The flow diagram according to FIG. 6 shows a situation in which the abovementioned processing sequences are continuous with one another in the device according to FIG. In step s1, the correction color is assigned to the RAM cell further associated with each CCD pixel using one of the processes described above. In step s2, three patterns for the three colors are displayed, resulting in an image such as the image displayed in FIG. In step s3, color red R is set as the first color F to be tested first,
The x direction is selected as the coordinate k. With these data, the color R and the center point SFk of the coordinate x are calculated as described with reference to FIG. The calculated value is accumulated (step s4). At step s5, a determination is made whether the coordinate has the value x. If so, step s6 is reached and the coordinates are set to the value y. Step s4 is performed again, which is the color as shown with reference to FIG.
This means that the center point SFk of R and the coordinate y is determined from the RAM data. The calculated value is accumulated. Instead of the above process, the x and y coordinates of the center point of the color red pattern are also determined using the process described with reference to FIG.

If it is clear in step s5 that the coordinate is not x, step s7 asks if the color is R. As it is in the present example, step s8 is reached, the coordinate k is reset to the value x and the color is set to the value G. The center point is determined with respect to the G pattern as described in the R pattern. When step s7 is reached again, the color is not R, and it leads to step s9, which asks if the color is green. If the color is green, step s
10 is reached, the coordinate k is set to the value x, and the color G [si
c] is selected as the color. Again the center point is determined in the manner described above. When the step s9 is reached again, the color is not green, but it is guided to the step s11, in which the difference between the center points of the green pattern and the center points of the red and blue patterns is calculated. Since the difference between the center points of the brightness distribution does not exactly match the difference between the center points of the actual pattern, in step 12, the difference between the coordinates of the center points of the brightness distribution pattern is Converted to the difference between coordinates.

The use of an image segment having a green part extending diagonally in the slot direction, in particular of a rectangular form with one vertex, is described in German Patent Specification DE-A-32.
Known for different content by 06 913. However, the process described herein involves producing a pattern of morphology, which in turn allows vertical or horizontal raster lines to be passed through by a mask having the pattern. Raster lines do not enter and leave the mask at the same time if vertical lines are included and horizontal convergence error is present, these operations occur sequentially. The use of a mask of the form described above leads to a signal of increased amplitude, from which the offset is estimated over time in amplitude. This value very accurately indicates the convergence offset. However, the use-guided implementation of the aforesaid device of the aforesaid apparatus is unusable in the case of the present invention, since the time-related profile is not tested, and instead an analyzed single image of a particular pattern is used. Are stored and analyzed.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a color picture tube and apparatus for measuring the electron beam convergence and raster position of the tube.

FIG. 2 is a rectangular emission spot pattern and an image converter that stand at the top when imaged by a CCD image converter.
FIG. 3 is a schematic diagram of a luminance distribution along a horizontal line of the data.

3A and 3B are a diagram corresponding to FIG. 2A in which the pattern is displaced slightly to the right, a diagram in which the pattern is displaced slightly downward in comparison with the position, and a luminance distribution diagram thereof.

FIG. 4 is a diagram of patterns at two positions in the field of view of a convergence converter.

FIG. 5 is a 30 [sic] partially overwrapped pattern diagram of the field of view of an image converter, each pattern belonging to one of three different electron beams.

6 is a flow chart of processing performed by the apparatus according to FIG.
Fig.

FIG. 7 is a schematic view of a known device corresponding to FIG.

8 is a schematic view of the CCD image converter and associated RAM of the device according to FIG.

FIG. 9: Screen of fluorescent stripes and emission spots on the screen and associated luminance measurement curves.

FIG. 10 is a view corresponding to FIG. 2 using a normal pattern.

Front page continued (72) Inventor Celio Zernhorst Germany, 3100 Celle, Telefunkenstraße 3 (72) Inventor Gunter Bessels Germany, 2805 Stower 4, Nechtersberger Strasse 7

Claims (6)

[Claims] 1. An electron beam for producing a brightness distribution pattern of a screen of a tube, a screen having fluorescent stripes of different colors, a shadow mask, and a screen existing in front of the fluorescent stripes. , A slot extending to the fluorescent stripe direction is used, and an image converter that generates a pre-defined electron distribution pattern on the shadow mask and converts the brightness distribution pattern into an electron charge pattern is used. And storing the relevant brightness distribution pattern on the screen and analyzing the charge pattern to obtain variable values characterizing the position of the charge pattern within the field of view of the image converter. In a method for measuring the position of an electron beam of a multi-beam color picture tube with respect to the field of view of an image converter, the generated electron distribution pattern has a dimension of the order of a few millimeters and at least one Parts extends obliquely to the longitudinal direction of the mask slots, associated brightness distribution pattern -
The electron beam of the color picture tube is characterized in that it is imaged on the image converter so that it fits perfectly in the field of view.
How to measure the position of the frame. 2. A method according to claim 1, wherein all edges of the electron distribution pattern extend obliquely to the longitudinal direction of the mask slot. 3. A variable according to claim 1, wherein the variable characterizing the position of the charge pattern in the image converter is the charge center point in a predetermined direction. Method. 4. The variable characterizing the position of the charge pattern within the image converter is the position of the edge of the charge pattern which extends perpendicularly to a pre-defined direction, essentially all The individual charges are located below the threshold of one region on the side of the edge, essentially all individual charges are located above the threshold of the region on the other side of the edge. The method according to any one of claims 1 to 2, characterized in that: 5. A method for measuring the position of at least two electron beams with respect to each other using the pattern, the scale for imaging the luminance distribution pattern of an image converter. Is selected so that all luminance distribution patterns are imaged, the color of the phosphor that emits light is determined for each pixel of the image converter, and the electron distribution pattern is measured. The images of the corresponding brightness distribution patterns, which are generated simultaneously for all the electron beams to be stored, are stored by the image converter and are different for each of the two electron beams in the direction perpendicular to each other. 5. A method according to any one of claims 1 to 4, characterized in that the analysis of the stored image is carried out using the assignment of pixels to electron beams. 6. An electron beam for producing a brightness distribution pattern of a screen of a tube, a screen having fluorescent stripes of different colors, a shadow mask, and a screen in front of the fluorescent stripes. And a slot extending in the direction of the fluorescent stripes, and a pattern generator for generating a pre-defined electron distribution pattern on the shadow mask and an associated brightness distribution pattern on the screen. An image converter camera for recording, an image converter for converting the brightness distribution pattern recorded by the camera into an electric charge pattern, and a charge pattern within the field of view within the image converter. Analyzer for analyzing the charge pattern to obtain the value of the variable characterizing the position of, and sequence control for controlling the sequence over time of the pattern generator, the image converter and the analyzer. Image converter; and a location - multiple related field of data bi - Mukara -
In an apparatus for measuring the position of an electron beam in a picture tube, a pattern generator produces an electron distribution pattern having dimensions on the order of a few millimeters, at least one edge of which is the length of a mask slot. An image of a color picture tube which extends obliquely with respect to the direction and is characterized in that the image converter camera images the luminance distribution pattern on the image converter so as to perfectly match the field of view. Beam position measuring device.